This article reviews recent recreation ecology research focused on developing new survey methods for assessing formal and informal trails or unsurfaced roads in wilderness and backcountry settings (fig. 1). Recreation ecology examines resource impacts caused by or related to visitor use. A brief review of research related to trail sustainability is included to illustrate factors that influence common types of trail degradation. These studies are producing new information and tools for park managers engaged in trail, carrying capacity, and other park planning and management decisions. Results can document the nature and severity of trail impacts and design deficiencies for planning and management decision making. For example, such data can justify staffing and funding requests to improve trail sustainability by relocating or reconstructing the worst trail segments, which will lower recurring maintenance costs.

Many park trails, especially those created before the advent of modern trail construction guidelines, were not sustainably designed. It is not surprising, therefore, that some park wilderness and backcountry trail systems quickly degrade under heavy traffic (fig. 2). A survey of National Park Service (NPS) backcountry and wilderness managers found that trail impacts were regarded as the most severely pervasive visitor impact problem, with 50% of all parks reporting trail impacts occurring in most or many areas (Marion et al. 1993). The most common trail impacts reported by park staff included soil erosion (44% of parks), trail widening (31%), braided/multiple trails (29%), informal trails (29%), and excessive muddiness (25%). These trail-related impacts are of great concern in wilderness areas (Abbe and Manning 2007), which are managed to maintain resource conditions that are “untrammeled by man … protected and managed so as to preserve [their] natural conditions” (16 USC 1131–1136). Moreover, trails that are designed or reworked to meet sustainability guidelines can reduce future maintenance costs and conflicts with the “minimum tool” wilderness management requirements.